Multifunctional wearable electronic textiles based on interfacial polymerization of polypyrrole on carbon nanotubes/cotton fibers offer advantages of simple and low-cost materials that incorporate bactericidal, good electrochemical performance, and electrical heating properties. The high conductivity of doped polypyrrole/CNT composite provides textiles that reaches temperature on order of 70 °C with field of 5 V/cm, superior electrochemical performance applied as electrodes of supercapacitor prototypes, reaching capacitance in order of 30 F g and strong bactericidal activity against Staphylococcus aureus. The combination of these properties can be explored in smart devices for heat and microbial treatment on different parts of body, with incorporated storage of energy on textiles.

No abstract

No abstract

The development of highly conductive, flexible, mechanical reinforced and chemically modified cotton yarns for electrodes of supercapacitors represents an important advance in the energy storage devices applied in wearable electronics. The production of carbon-based conductive layers as supports for chemical polymerization of active polymeric materials (such as polypyrrole) is an important strategy that associates the high electrical double-layer capacitance of the carbon derivatives (carbon nanotubes and graphene nanoplatelets) and the pseudocapacitance of the polypyrrole in truly flexible devices with improved electrochemical response-high capacitance. These properties are affected by relative concentration of graphene nanoplatelets in carbon complexes due to the variation in overall conductivity of electrodes (in consequence of low aggregation degree and available surface area) and the electrochemical properties of the resulting devices that reaches capacitance in order of 45.5 F g −1 with a capacitive retention of 70% after 2000 cycles of use. These promising results open possibilities for new systems in wearable electronics.

Preparing sustainable and highly efficient biochars as electrodes remains a challenge for building green energy storage devices. In this study, efficient carbon electrodes for supercapacitors were prepared via a facile and sustainable single-step pyrolysis method using spruce bark as a biomass precursor. Herein, biochars activated by KOH and ZnCl2 are explored as templates to be applied to prepare electrodes for supercapacitors. The physical and chemical properties of biochars for application as supercapacitors electrodes were strongly affected by factors such as the nature of the activators and the meso/microporosity, which is a critical condition that affects the internal resistance and diffusive conditions for the charge accumulation process in a real supercapacitor. Results confirmed a lower internal resistance and higher phase angle for devices prepared with ZnCl2 in association with a higher mesoporosity degree and distribution of Zn residues into the matrix. The ZnCl2-activated biochar electrodes’ areal capacitance reached values of 342 mF cm−2 due to the interaction of electrical double-layer capacitance/pseudocapacitance mechanisms in a matrix that favors hydrophilic interactions and the permeation of electrolytes into the pores. The results obtained in this work strongly suggest that the spruce bark can be considered a high-efficiency precursor for biobased electrode preparation to be employed in SCs.

The development of supramolecular structures (conducting hydrogels) obtained from the charge–charge interaction of sodium dodecyl sulfate micelles and oppositely charged polypyrrole chains represents an important step to obtain self‐supported and flexible electrodes for supercapacitors. Herein, the energy density of polypyrrole hydrogel‐based supercapacitors is enhanced by the incorporation of graphene nanoplatelets that introduced the electrical double capacitance contribution to the overall response. The electrochemical performance of synthesized electrodes was optimized from the relative variation in the concentration of supramolecular arrangements (micelles of sodium dodecyl sulfate), pyrrole, and graphene nanoplatelets. As result, higher capacitive retention is observed for modified electrodes (with the incorporation of graphene) – in order of 90% after 1000 cycles of use, preserving the high conductivity and intrinsic mechanical properties (flexibility and stretchability) reaching an areal capacitance of 210.7 mFcm−2.

The development of implantable and wearable electronics and the concept of the internet of things proved a recent burgeoning growth with different applications. However, the integration of electrically driven devices depends on hard components that must be conveniently substituted by flexible and more efficient devices. Herein, the development of a simple and low-cost all-in-one flexible system based on triboelectric generators that harvest energy from the skin contact with the device is proposed and makes possible the storage of this energy in a supercapacitor prepared with the same support applied as collectors of triboelectric nanogenerators (eggshell membranes modified with graphene nanoplatelets and polypyrrole). This integrated prototype for the energy harvesting/storage device with the characteristic flexibility of natural eggshell membranes introduces promising properties of an autonomous device able to drive electronic devices integrated into flexible substrates.

Capacitors are a ubiquitous component of many modern-day electronics that provide remote sensing, power conditioning, electrical noise filtering, signaling coupling or decoupling, and short-term memory storage. With the desire for flexible, smaller, and more powerful electronics, capacitors and other electrical components will have to be improved to meet these growing demands. Carbon-derived materials are good candidates for use as electrodes in electrochemical capacitors (i.e., supercapacitors) because of their nanoscale and flexible architecture. However, implementations of these materials tend to have inferior specific capacitance and energy density compared with other options. In this work, different carbon derivatives (graphene oxide, Claisen graphene, activated charcoal oxide, and activated charcoal Claisen) were chemically modified via nitrogen doping to optimize the capacitance, power density, energy density, and the overall electrochemical performance of the resulting supercapacitors. Devices with a two-electrode configuration were assembled and confirmed the superior performance for all N-doped carbon derivatives in all analyzed parameters (specific capacitance, energy density, and power density) when compared with their undoped counterparts. The maximum areal capacitance obtained was 421.44 mF/cm2 for the N-doped activated charcoal oxide, which represents an improvement of 242.2% in comparison with the corresponding nonmodified sample, in addition to a 153% improvement in the energy density and strong retention in specific capacitance (in the order of 86% at 1000 cycles of operation).